I am no expert, but I think that you'd claim for the VAT refund in Rome (leaving the last EU country you visited). Be aware that with LV you have to take your passport to the store -- they don't accept pictures of your passport like most other designer stores do. Are you looking at buying a Goyard bag in Paris? Sometimes their stores have long lines to get in; I prefer the Goyard store in Printemps since it seems to have shorter lines. Everything else being equal, I'd wait until Rome to make the purchases so you don't have to lug them around Europe (unless you want a Goyard, in which case you'd have to purchase in Paris since they don't have a store in Rome).